The present invention relates to an actuator, and more particularly to a drive mechanism providing accurate feedback and to a quick coupling visual indicator for opposed coaxial shafts.
Traditionally, fuel and air valve dampers for boiler applications have only been coupled via mechanical coupling arrangements. Such arrangements were quite complex and cumbersome. In attempting to develop an electronic interlock for such dampers (valves), one hindrance in achieving appropriate coupling was the need for very precise rotational coupling of coaxially aligned shafts in an actuator mechanism.
Known axial coupling or drive mechanisms use pins, tabs and keys as the coupling means for transferring rotary movement from one shaft to another shaft when it is desired to allow relative freedom of movement in the axial direction. However, these known coupling mechanisms do not provide a suitably precise level of positional accuracy for some purposes, and particularly for those where precise electronic interlocking of opposed axial members is desired. In addition, Field service and adjustment may be needed from time-to-time for such mechanisms. Accordingly, their reassembly in the field after maintenance and trouble-shooting should be simple and should result in quick and accurate realignment of any mechanical coupling arrangements therein.
The present invention is a mechanism for rotatably coupling two shafts in generally coaxial alignment. The mechanism includes a female socket and a male fitting that allow relative movement of the shafts in the X, Y and Z directions while maintaining precise rotational alignment of the shafts.
In one embodiment, the invention is a mechanism for rotatably coupling a first shaft and a second shaft in generally coaxial alignment which includes a female socket and an opposed male fitting. The female socket is rotatably coupled to the first shaft, and has a generally cylindrical column section with a plurality of equally spaced apart receiving channels defined on an inner circumferential side thereof. The male fitting is rotatably coupled to the second shaft, and has a plurality of radially extended arms thereon. Each arm has at least two circumferentially flexible fingers projecting radially therefrom. The fingers of each arm are slidably received within one of the receiving channels of the female socket, thereby connecting the first and second shafts for coupled rotation, yet allowing limited relative movement of the first and second shafts in the X, Y and Z coordinate directions.
Another aspect of the invention is the affirmative rotational coupling of two shafts in generally coaxial alignment by use of opposed yet biased together cams. The two shafts may be axially disengaged and then readily re-engaged and aligned in their prior rotational alignment, by operation of the engaging cam structures.